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I have a 97 impreza outback sport and yesterday the power started to cut in and out like a bad battery/ground connection. earlier that day I had swapped my battery with someone at the river that had left there lights on. and didn't have the proper tools to tighten it back up so that's what I thought was happening. but I start to smell soothing burning and notice a light from a fire by my feet. so I stopped to check it out at and notice it was my clutch cable arcing and almost catching fire. I do notice when I push down on the clutch just a nuff that the peddle meets the cable it stops and I regain power as if it is grounded


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The clutch cable and positive are no where near touching. And neither of the cable have been rerouted. My positive terminal on the cable won't tighten all the way. Yes battery has been out. So I'm just gonna get new terminals and check all grounds and cables

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Ground was on pretty tight and is grounded to motor and frame. but just in case I have got some extra wire and will redo the ground. I'm also replacing positive terminal seeing how it was messed up enough that I couldn't tighten it.thanks for everyone's help and will update one I get the new terminal on.

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If the fire is inside the car........Your clutch pedal is cutting into the ignition switch harness.  Check the pivot area of the clutch pedal.

 

if the fire is in the engine bay.....I woudl guess the cable is hitting the pos. battery cable at the starter end.

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Sounds like you have some SERIOUSLY worn out ground connections from engine-to-body, and the clutch cable is acting as a surrogate ground. Go to AutoZone or whatever is close, and buy some generic ground cables. I like the braided steel grounds for this. Find a good spot on the body and grind the paint back, and run a bolt and nut through it. Ground the strap there and use a spot on the engine for the other end (I suggest coating the bare metal with a conductive paste). I recommend doing TWO of these. One near the starter, and another near the alternator. Replace the clutch cable. Inspect BOTH the ground cable off the battery AND the 12v+ cable off the battery, ALL the way back to the starter. If either have hardened, you'll need to replace them as well. Go back and inspect ALL the engine bay lesser ground wires for corrosion, breaking, hardening (means they've been overheated) etc. and either splice in a new section and heat shrink the soldered point, or remove the corrosion and install new eyelets of excellent steel quality (no cheapy connectors here).

Edited by Bushwick
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  • 2 weeks later...

Unless he hooked his clutch cable to the battery.....the clutch is not providing a ground.

 

besides....he says here:

 

Ground was on pretty tight and is grounded to motor and frame.

 

 

It is touching and "grounding" the main power wires under the dash.  When that happens power goes away.

 

Seen it before.....sometimes happens with steering tilt lever too.  Ussually a sign someone has been up under the dash doing things.

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Well, a tight connection in no way guarantees a good electrical connection. There can be unseen corrosion affecting continuity.

IMO, if the main power wires under the dash were grounding, I'd think that the wires would arc and perhaps blow some fuses. The OP states that the clutch cable was arcing, not any wires, and the arcing stopped when clutch pedal freeplay is taken up (ground circuit now being completed through the pedal). Another clue is that the arcing started only after the battery was changed without any work having been done under the dash.

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Yeah, just because ground cables "look" OK, doesn't mean they are. My guess is the clutch cable is moving and the outer casing is arcing when it's making direct contact on the sides, Otherwise it's grounding internally. This would suggest weak grounds to the body and/or engine or even at the battery. My old 79' Mustang with a 306 transplant from a 4cyl didn't have enough grounds, but it still started OK when I bought it off my step dad. Then it wouldn't crank. Noticed cables hardening. Replaced them, same thing. Replaced again, but added extra ground straps to the block and body and the car never had any more issues starting. Before adding ground straps and trying to figure out why it wouldn't start (20 years ago), I took a 4-way tire iron and grounded directly the body to the block, and had someone crank it. It immediately fired and the tire iron sparked. This let me know there either weren't enough grounds, or something was wrong with them.

 

It takes 15 minutes and $15 roughly to add a redundant ground (never hurts anyways on older cars that see salted roads as their ground points deteriorate over time) and see if the arcing stops. If the clutch cable was hitting a 12v+ source, it'd either pop fuses or weld the cable up at the arc. IF it's the only solid ground left and a huge amount of current is being pulled from it (12v-) that can destroy the cable but shouldn't pop any fuses. 

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I doubled up the ground from the battery, bolted an eyelet-ended cable to each end. The OEM cable is made of very fine strands of copper.

After 10 years or so, depending on use/environment/etc. those very fine strands seem to have corroded nearly through.

The connection between the copper and the clamp is subject to corrosion too.

 

IDK if corrosion occurs only at the surface, but fine wire has a lot more surface area than thick wire per total cross section area.

 

 

Well, a tight connection in no way guarantees a good electrical connection. There can be unseen corrosion affecting continuity.

IMO, if the main power wires under the dash were grounding, I'd think that the wires would arc and perhaps blow some fuses. The OP states that the clutch cable was arcing, not any wires, and the arcing stopped when clutch pedal freeplay is taken up (ground circuit now being completed through the pedal). Another clue is that the arcing started only after the battery was changed without any work having been done under the dash.

Edited by uniberp
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^ Any are of the cables that are exposed, can/will corrode if no grease or other protectant is applied. I had an issue with an 84' Laser where the cables had corroded AT the battery clamps, right where it entered the lead area. Visually it "looked" OK, but it wasn't. I bought a set of universal battery post clamps and cut the factory wire back to clean copper, then inserted into new clamps. Car actually ran better and pulled stronger from what I remember, so they were pretty well shot to the point they were limiting current. That car was fuel injected and had an ecm. The 79' Mustang had a mechanical fuel pump and only electronics were the ignition coil, so once that started, it remained running.

 

Anyways, maybe the topic starter will update and let us know he fixed it as this thread is a little old?

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Well, a tight connection in no way guarantees a good electrical connection. There can be unseen corrosion affecting continuity.

IMO, if the main power wires under the dash were grounding, I'd think that the wires would arc and perhaps blow some fuses. The OP states that the clutch cable was arcing, not any wires, and the arcing stopped when clutch pedal freeplay is taken up (ground circuit now being completed through the pedal). Another clue is that the arcing started only after the battery was changed without any work having been done under the dash.

 

If the clutch cable isn't connected to the battery.....it cannot provide a ground.   Something has to be connected to the negative post of the battery.   Period.  I don't understand why this is a hard concept.

 

How would the cable be connecting to the battery?  Are you saying the engine is grounded but the chassis is not?  There would have to be several disconnected grounds for this to happen.  Battery to frame (which he states is in place) And the wire from back of trans to firewall, And the wire from the passenger side PS bolt to the chassis......as well as all the ECU grounds that go to the Engine.  The engine would not cut out power even if the Chassis was COMPLETELY disconnected from ground as the ECU is grounded through the intake manifold bolt.

 

I bet dollars to donuts that the clutch pedal is hitting either the White or the Blue Main power leads.....Which have only fusible links upstream so no fuse would blow and would take several seconds of arcing/shorting to melt the FL.

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If the clutch cable isn't connected to the battery.....it cannot provide a ground.   Something has to be connected to the negative post of the battery.   Period.  I don't understand why this is a hard concept.

How would the cable be connecting to the battery?  Are you saying the engine is grounded but the chassis is not?

The clutch cable is connected to the battery negative in the same fashion as scores of other devices; through the body! In this case, gearbox>cable>cable bracket>body>battery.

 

"Are you saying the engine is grounded but the chassis is not?" (sorry, don't know how to multiquote the same post)

 

No. The other way round; chassis is grounded, engine is not (through the preferred path anyway).

 

"The engine would not cut out power even if the Chassis was COMPLETELY disconnected from ground as the ECU is grounded through the intake manifold bolt."

 

Please see previous answer. If the engine is not sufficiently grounded, then the ECU may not see system voltage potential and possibly shut down.

 

Compromised grounds of any kind in any circuit can result in all sorts of sometimes supernatural symptoms. With a bad engine ground, the electric will seek an alternative path of least resistance (if one is available). It might be another wire, a cable or even a hose with high surface conductivity. Could be anything! As an example, the alternative engine ground path for a SPICA fuel injected Alfa Romeo. if there is high resistance in/or a broken engine/gearbox ground strap, is the throttle cable.

 

Quickly and correctly diagnosing electrical faults even with a vehicle in the flesh can be a feat worthy of applause. Diagnosing over the internet introduces even more challenges. So without being able to conduct any hands on testing, my suggested diagnosis is based on knowledge and experience.

 

What would I test if I had the vehicle in front of me? Voltage drops between the negative battery post and cable clamp, battery post and chassis then battery post to engine. And under load if the results dicate it. Same on the positive side if necessary. To prove or disprove results, or maybe to not even perform the voltage drop tests at all, connect a jumper cable (as in battery jumper cables, not a household extension cord) between the negative cable clamp and engine then observe the results (hoping that the post to cable clamp connection is good).

 

Our common goal here is to help f1gelato diagnose and repair the problem while teaching a bit along the way.

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The clutch cable is connected to the battery negative in the same fashion as scores of other devices; through the body! In this case, gearbox>cable>cable bracket>body>battery.

 

"Are you saying the engine is grounded but the chassis is not?" (sorry, don't know how to multiquote the same post)

 

No. The other way round; chassis is grounded, engine is not (through the preferred path anyway).

 

If the Engine was not grounded, the car would not start as the starter grounds to the engine block.

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  • 3 weeks later...

Ive since changed all grounds and car is back to norm.

Awesome! Glad it's back to normal.

 

 

 

If the Engine was not grounded, the car would not start as the starter grounds to the engine block.

Gloyale, it has nothing to do with engine being grounded or not. If the negative ground isn't allowing full current to pass through, whether this is a result of missing or completely broken grounds, heavily corroded connections like green and brittle copper strands, etc. the current will find alternative means to make up for it. If you have a solid metal clutch cable with a solid steel casing, it'll ALWAYS act like a ground as it connects 2 different areas together. Since the factory ground wires are typically the shortest path from the battery to engine block/alternator, and are designed to handle loads of current, it's the path that's taken. If that cable isn't doing it's full job, the current will seek other grounds w/o prejudice if they are actually grounds or not. Think the fact replacing his grounds fixed the car, speaks volumes here.

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